DC/DC converter, and power amplifier applying the same

Abstract

A DC / DC converter capable of controlling an output signal using a broadband signal input is provided. By employing the above DC / DC converter as a power supply, a highly efficient power amplifier can be configured. The above DC / DC converter includes two class-C amplifiers, a rectifier circuit connected between each output of the two class-C amplifiers, and an oscillator of a predetermined frequency signal. The predetermined frequency signal output from the oscillator is input to each of the two class-C amplifiers, and by controlling the phase difference of the predetermined frequency signal input to the two class-C amplifiers, the magnitude of a direct current voltage output from the rectifier circuit is made variable.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of International Application No. PCT / JP2005 / 12027, filed on Jun. 30, 2005, now pending, herein incorporated by reference.FIELD OF THE INVENTION[0002]The present invention relates to a DC / DC converter, and a power amplifier applying the same.BACKGROUND OF THE INVENTION[0003]As the use of broadband in digital mobile radio systems spreads, even higher efficiency in a power amplifier is desired.[0004]Here, referring to FIG. 1, the input / output characteristic and the efficiency of an amplifier is examined. In FIG. 1, the horizontal axis is input power (W), the left vertical axis is output power (W), and the right vertical axis is efficiency. The input power versus the output power characteristic (input / output characteristic) I shows a characteristic that an output growth saturates when the input power (W) becomes a large level. Meanwhile, in regard to the efficiency, the efficiency is low in a region of a sma...

AI Technical Summary

Benefits of technology

[0012]Specifically, by increasing the drain voltage to 10, 15, 20 V, . . . or the like, according to the input power level of the power amplifier, the input / output characteristic of the power amplifier is varied. FIG. 5 shows a diagram illustrating that output saturation is given to the entire amplitude of the linearly modulated signal waveform of Quadrature Phase Shift Keying (QPSK), etc. shown in FIG. 3. In FIG. 5, to each varying amplitude level of the input signal (A in FIG. 5), an output saturation region in the corresponding input / output characteristic, that is, a maximum efficiency region can be given. In FIG. 5, B indicates a state in which an original voltage waveform (A in FIG. 5) is saturated because of the output saturation region in the input / output characteristic. By this, it becomes possible to obtain maximum efficiency of the power amplifier over the dynamic ranges of the input signal level.

[0018]According to the present invention, a DC / DC converter capable of controlling an output signal by the use of a broadband signal input can be provided. Also, using the above DC / DC converter as a power supply, a highly efficient power amplifier can be configured.

Problems solved by technology

However, since the frequency spectrum band of the FM analog modulated signal is broad, it is not advantageous in view of frequency use efficiency.

Therefore, it is difficult to increase the total efficiency of the power amplifier.

However, when a steep pulse of 256 GHz, etc. is used, because matching cannot be made, it is difficult to put into practical use.

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